It is time for Robert De Niro to stop doing self-parody and to start doing legitimate work again.

I don’t mean his unintentional self-parody, like “15 Minutes” (2001) and “City by the Sea” (2002), where he plays wan variations of the characters he’s famous for. Those films at least intended to let De Niro do his tough-guy thing, even if the screenplays didn’t let him live up to his dramatic potential.

I’m talking about the intentional self-parody he’s been doing the past few years. “Analyze This,” the 1999 hit that was his first major comedy role, succeeded in part because De Niro was skewing his public persona just enough to be surprising.

But since then, he has skewed his image in “The Adventures of Rocky & Bullwinkle” (2000), “Meet the Parents” (2000) and “Showtime” (2002), and now the element of surprise is gone.

“Analyze That,” the sequel to “Analyze This,” suffers from an even more damaging fact: Since the first film was released, “The Sopranos” has become a cultural phenomenon. (”Analyze This” was actually released two months after the first episode of “The Sopranos” aired, but no one was paying attention yet then.) Both films and the HBO series are about ruthless Mafia bosses who see psyhiatrists to help them sort out their feelings, particularly their parental issues. After 52 episodes of James Gandolfini going head-to-head with Lorraine Bracco, what can 95 minutes with De Niro and Billy Crystal show us that we haven’t already seen? The joke is old now.

(It does not help that “Analyze That” begins with a half-hearted parody of “The Sopranos.” A movie that is derivative should not remind the audience what it’s derivative of.)

De Niro’s character, New York mobster Paul Vitti, is in prison when “Analyze That” begins, but after a breakdown that manifests itself in Paul dancing around singing songs from “West Side Story,” he is released to the custody of his old shrink, Ben Sobol (Crystal). Ben has 30 days to get Paul competent enough to attend his parole hearing; otherwise, for reasons I don’t exactly understand, Ben will lose his license to practice psychiatry.

It’s a bad time for Paul to be out, though, because the two major crime families are feuding and each one wants him on their side. Paul, meanwhile, has to figure out who’s been trying to kill him, all while getting a non-Mafia job -- he tries selling cars, which seems about right for a former goodfella -- and staying out of trouble.

Crystal is doing his regular ol’ Billy Crystal shtick, which is either amusing or tired, depending on your perspective. (”I’m taking gingko beloba. It helps with my memory and I forget what else.”) The script, by Peter Steinfeld, Peter Tolan and Harold Ramis (who also directed), makes a lame stab at personal crisis for Ben, where the death of his father causes him to wonder if psychiatry is what he really wants to do with his life, but that thread is abandoned.

De Niro makes the worst mistake in trying too hard to be funny. The guy has a talent for comedy, but it needs to be a certain type; slapstick and goofiness are not his thing. If you’ll recall, the funniest role he’s played so far -- the protective father in “Meet the Parents” -- was funny mostly in his reaction to the lunacy around him, not by putting on a clown nose and doing pratfalls. De Niro the comedian needs to be a foil for the other characters. He should not be the headlining act.

“Analyze That” is not gross or annoying; it is simply bland. It ambles onto the screen and just sits there for 95 minutes, occasionally earning a laugh but mostly just sitting there.